Automatic telephone system.



J. W. LATTIG &C. L. GOODRUFJL AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED APR.25. 19:6.

//7 V/7/J/5.' Jacob W La/f/g. Char/e51. Good/am.

UNITED STATES PATENT OFFICE.

JACOB W. LATTIG, OF GLENSIDE, PENNSYLVANIA, AND CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 1, 1918.

Application filed April 25, 1916. Serial No. 93,385. I

To all whom it may concern:

Be it known that we, JAcoB W. LATTIG and CHARLES L. GooDRUM, citizens of the United States, residing at Glenside, 1n the county of Montgomery and State of Pennsylvania, and at New York, in the county of New York and State of New York, respectively, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone systems, and more particularly to a system in which a calling subscriber can hold a connection which has been connected to a busy line, the talking strands of which are maintained open, and be automatlcally connected to said line for conversation when it becomes idle.

The object of the invention is to provide means to hold connections when they have been switched to a busy line in which the talking strands are maintained open, and to automatically establish the conversational circuit with but one of said calling lines when said called line becomes idle.

The invention is illustrated in the accompanying figure which shows in diagrammatical form a connection between tWo subscribers, the circuits of the connector being shown in detail.

In the embodiment of the invention shown in the figure, the invention is associated with a two-wire automatic system, but it will be understood that it may be readily applied to any one of the well-known types of automatic systems.

In the system illustrated, when the calling subscriber removes his receiver from the hook, the line finder 4. shown diagrammatically in the figure, will be switched to the contacts of the calling subscribers line. When the calling subscribers line has been connected through to the line finder, he will operate his impulse transmitter and thereby send a series of impulses to connect the movable contacts of the first selector 5, diagrammatically shown, with the terminals of a trunk leading to a connector containing the terminals of the desired called subscribers line.

When the calling subscriber has been connected to the connector, he Will send a second series of impulses over the line to select the group of contacts of the connector switch which contains the terminals of the desired called line. Immediately upon being connected to the trunk terminals leading to the connector, the line relay 6 will be operated and the operation of this relay completes a. circuit from the ground at its armature by way of its make contact and the slow acting relay 7 to battery. Consequently, when the calling subscriber sends the series of impulses to select the desired group of contacts in the connector, the armature of line relay 6 will vibrate and will close a circuit from the ground at its armature by way of its break contact, the right hand armature and make contact of relay 7 and the slow acting relay 8 to battery. This last circuit contains a parallel branch which may be traced from the right hand armature and make contacts of relay 7 by way of the break contact and armature of relay 9, the side switch arm 11 and the primary magnet 12 to battery. The operation of the primary magnet 12 will set the movable contacts 14 of the connector switch in alinement with the group of contacts of the contact bank of the connector which contain the terminals of the desired line. The operation of the slow relay 8 will close a. circuit from the ground at the armature and make contact of relay 7 by way of the make contact and armature of relay 8, side switch arm 15 and the side switch escape magnet 16 to battery.

After the subscriber has transmitted the first set of impulses to the connector, the line relay 6 will again be permanently operated for a definite period, and this will open the circuit of the slow acting relay 8 which will therefore be deenergized. The deenergization of the slow acting relay 8 opens the circuit of the escape magnet 16 and this will move the side switch of the connector into its second position.

The calling subscriber will now send a.

second series of impulses which will again vibrate the line relay 6, and since the side switch arm 11 is in its second position the secondary magnet of the connector switch will be operated to move the contacts 14 of the connector switch to the terminals of the desired line. When the movable contacts 14 connect with the terminals of the desired line, which will be assumed to be busy, a circuit will be established from the ground existing on the test conductor, by vlrtue of the line previously connected to the mult ple contacts of this line, through the test wlper of the movable contacts 14, the side switch arm 20 and the right hand winding of the test relay 9 to battery. This will cause the energization of the test relay whlch W111 complete a locking circuit for itself by way of ground, its left hand winding, make contact and armature of the relay and the brush and one disk of the interrupter 21 tobattery. The operation of the test relay 9 will likewise close a circuit from the ground at its middle left hand armature, the make contact, side switch arm 15 and the escape magnet 16 to battery. This circuit will cause the continued energization of the escape magnet 16, and consequently prevent the movement of the side switch arms of the connector switch into the third position.

In this second position of the side switch, a busy tone will be sent to the calling subscriber by means of a circuit which may be traced from ground through winding 24 of the transformer, side switch arm 25, olfnormal contact 26 of the connector switch to the lower side of the calling subscribers line, through the subscribers loop and back over the upper side of the subscribers line and the coil 27 to battery and ground. This busy signal will inform the calling subscriber that the line desired is busy and the subscriber may then at his option either hang up and release the connection, or wait at his telephone until the desired subscribers line becomes idle, at which time his line will be automatically switched into connection with the desired line.

It will be assumed that the calling subscriber is holding the connection until the desired called subscribers line becomes idle. In this case, when the called line becomes idle the ground will be removed from the multiple test conductor and this will open the energizing circuit of the right hand winding of the test relay 9. It will be remembered, however, that this test relay in operating closes for itself a locking circuit by way of its armature and one disk of the interrupting device 21. The interrupting device 21 consists of a constantly rotating shaft on which are mounted a series of metallic disks, each one of which is equipped 'in its periphery with an insulated-segment.

These insulated segments in the various disks are angularly displaced around the circum ference so that the insulated portion of the disk assigned to any particular connector switch will contact with its corresponding wiper brush at a time when the brushes of all the other disks are connected to the metallic portion of the disk. Consequently, when the energizing circuit of the right hand winding of the test relay 9 is opened, this relay is retained in its operated position by the circuit completed through one of the disks of the interrupter 21 and when the brush allotted to the particular connector rides on the insulated portion of its associated disk this circuit will likewise be opened and the test relay will be de'elnergized. The deenergization of the test relay 9 will open the circuit of the escape magnet 16 at its-middle left hand armature, and consequently the arms of the side switch will move into their third position. In the third position of the side switch a circuit is completed for the escape magnet 16 from battery through its operating winding, side switch arm 15, the armature and break contact of ringing relay 30 and the make contact and left hand armature of the slow acting relay 7 to ground. This circuit will hold the escape magnet of the side switch in its energized position and this circuit is controlled by the armature of the ringing relay 30.

The operation of the escape magnet 16 closes a circuit from the generator 31 through the winding of the ringing relay 30, the armature and make contact of the escape magnet 16, side switch arm 32, the lower side of the trunk and thenceby way of the lower side of the line through the called subscribers loop and back over the upper side of the line and trunk and side switch arm 33 to ground. This will apply ringing current to the called subscribers line and when the subscriber answers, the flow of current through the called subscribers loop will increase sufficiently to energize the ring ing relay 30, which in energizing will open the energizing circuit of the escape magnet 16, which in turn will cause the movement of the side switch arms into the fourth position, thereby completing the conversational circuit from the calling to the called subscribers.

When the subscribers have completed their conversation they will hang up their receivers. The calling subscriber in hanging up his receiver will open the circuit of the line relay 6, and this will close a circuit from the ground at its armature by way of the break contact, the right hand armature and break contact of relay 7 and through the off-normal contact 35 and the release magnet 36 to battery. This will energize the release magnet 36 of the connector switch Serial No. 872,743, filed November 18, 1914.

The circuits of the figure show three test relays multiply connected to the test wire of the called line when the test brush contacts with its associated. test contact, and it will be obvious that all the test relays of the connectors of a group Will be connected in a like manner. Each of these test relays is provided with a locking winding, one terminal of which is connected to ground and the other is wired through a disk of the inter-' rupter 21. Therefore, as these disks are all equipped with insulated segments which are angularly displaced with respect to one another in the circumference of the disks, the locking circuits of the various test relays will be opened, one at a time in succession, as the brush allotted to each disk comes in contact with the insulated segment. It will therefore be obvious it several subscribers attempt to call a line which is busy and they all hold the connection so as to be switched into circuit when'the called subscribers line becomes idle, but one of these subscribers can be connected to the called subscribers line at a time. This follows from the fact that the movement of the side switch arms into the third position is controlled by a make contact on the test relay 9 and the side switch will therefore not move into its third position until the test relay 9 is dee'nergized.

Further, since the test relay is locked by means of its left hand winding by a circuit wired through one disk of the interrupter, the test relays of all the calling lines connected to a busy called subscribers line that has been rendered idle, will be energized through these locking windings. Since these locking windings of the various test relays will be opened one at a time in succession due to the angular displacement of the insulated portions in the disks of the interrupter, but one subscriber can be connected at a time to the terminals of the desired called line.

As has been previously stated the interrupter 21 is provided with a series of disks Obviously the invention is not limited to the specific embodiment herein shown and despribed, but is capable of many variations andapnucations without departing from its spirit and scope.

hat is claimed is:

1. In an automatic telephone system, the combination with a plurality of calling subscribers lines, of engaged subscribers lines, means to switch said calling lines to the termmals of an engaged subscribers line, means to maintain the conversational circ u1ts of said lines to said busy subscribers llne open when so connected, and means when said called subscribers line becomes idle to automatically complete the conversational circuit of one only of said plurality of calling subscribers lines to sald called subscribers line.

2. In an automatic telephone system, the combination with a plurality of calling subscribers lines, of engaged subscribers lines, means to swltch said calling lines to the termlnals of an engaged subscribers line, means to maintain the conversational circuit of said lines to said busy subscribers line open when so connected, and means as said called subscribers line becomes repeatedly idle to automatically complete in succession the conversational circuits from said plurality of calling subscribers lines to said called subscribers line.

3. In an automatic telephone system, the combination with a plurality of calling subscrlbers lines, of engaged subscribers lines, means to switch said calling lines to the terminals of an engaged subscribers line, means to maintain the conversational circuit of said lines to said busy subscribers line open, means to transmit a busy signal to said calling subscribers line, and means when said called subscribers line becomes idle to automatically complete the conversatlonal circuit of one only of said plurality pf calling lines to said called subscribers 4. In an automatic telephone system, the

combination with a plurality of calling sub scribers lines, of engaged subscribers lines, means to switch said calling lines to the terminals of an engaged subscribers line, test relays operated to maintain the conversational circuit of said lines to said busy line open, and means to denergize one only of said test relays when the called subscribers line becomes idle to complete the conversational circuit of the associated calling line with said called subscribers line.

5. In an automatic telephone system, the

combination with a plurality of calling sub-v scribers lines, of busy subscribers lines, means to switch said lines to the terminals of a busy subscribers line, relays for testing the condition of said called line and operated to prevent the closure of the conversa- In Witness whereof, I hereunto subscribe fional clrcuit of the calling line which has my name this 22nd day of April, A. D. 10 been switched to the terminals of the busy 1916.

called line, and an interrupter for deener- JACOB W. LATTIG.

o'zin one onl of Slld rel" s whe s 5 y 11 ad In wltncss whereof, I hereunto subscrlbe called line becomes idle to connect one of said p y of calling lines with Sai (1 my name tlns 7th day of Apnl, A. D. 1916.

called line. CHARLES L. GOODRUM. 

